MMV and GSK today announced positive results from two phase III studies of tafenoquine, an investigational 8-aminoquinoline, for the prevention of relapse of Plasmodium vivax (P.vivax) malaria.

The headline results, presented today at the International Conference on Plasmodium vivax Research (ICPVR) in Manaus, Brazil, show that a single-dose of 300mg tafenoquine, when given with a 3-day blood-stage chloroquine treatment, reduced the risk of relapse in patients with P.vivax malaria significantly more than placebo when given with chloroquine.

P. vivax is one of several species of Plasmodium parasite known to cause malaria. After an infected mosquito bite, the parasite has the ability to lie dormant in the liver and periodically reactivate causing relapses of P. vivax malaria. These relapses can occur weeks or even years after the initial infection. The disease is estimated to cause around 8.5 million clinical infections every year.1 Each of these infections keeps a child or adult from school or work for at least 3 days.2 Studies have shown that beyond lost time, malaria can also have adverse effects on cognitive ability.3,4

Since 2008, GSK and MMV have been working together to develop single-dose tafenoquine as an alternative to the existing standard of care, primaquine, which must be taken for 14 days for patients with the relapsing form of malaria. The two phase III randomised, double-blind studies, “DETECTIVE” and “GATHER”, were conducted in malaria-endemic countries covering South America, Asia, and Africa.

Patrick Vallance, President, GSK R&D said: “One of the greatest challenges for patients with P. vivax malaria is preventing relapses. Being able to treat patients with a single dose of medicine would be an important step forward in ensuring efficacious treatment, thereby reducing the risk of relapse, particularly in areas with very limited healthcare infrastructure. We are grateful to the dedication and commitment from the patients, investigators and community workers who took part in this study, some of whom live in remote areas with little or no access to healthcare. Malaria remains a leading cause of death and disease in many developing countries and at GSK we are committed to play a role to support the World Health Organization’s goal to end malaria for good. As part of these efforts, our aim is to make tafenoquine available and affordable as a single-dose medicine in malaria-endemic countries.”

David Reddy, CEO of Medicines for Malaria Venture said, “The positive results of the phase III trials for single-dose tafenoquine provide great hope that a new, effective drug to stop the relapse of P. vivax malaria is in sight. Relapsing malaria places a heavy burden on the world, infecting over 8.5 million people a year. Without treatment to eliminate the dormant form of the parasite, patients live with the disease, never knowing when it will relapse and when its debilitating symptoms will return. Not only could single-dose tafenoquine help to put a stop to the relapse for individual patients but it could also help make malaria elimination a real possibility in P. vivax endemic countries. Our successful partnership with GSK on the development of this important medicine is the product of joint commitment to eliminate this terrible disease.”